I. Field
The present invention relates generally to communication, and more specifically to data transmission in a communication system.
II. Background
In a communication system, a transmitter typically encodes, interleaves, and modulates (i.e., symbol maps) traffic data to obtain data symbols, which are modulation symbols for data. For a coherent system, the transmitter multiplexes in pilot symbols with the data symbols. Pilot symbols are modulation symbols for pilot, which is data that is known a priori by both the transmitter and receiver. The transmitter further processes the multiplexed data and pilot symbols to generate a modulated signal and transmits this signal via a communication channel. The channel distorts the transmitted signal with a channel response and also degrades the signal with noise and interference.
The receiver receives the transmitted signal and processes the received signal to obtain received data symbols and received pilot symbols. For a coherent system, the receiver estimates the channel response with the received pilot symbols and performs coherent detection on the received data symbols with the channel response estimates to obtain detected data symbols, which are estimates of the data symbols sent by the transmitter. The receiver then deinterleaves and decodes the detected data symbols to obtain decoded data, which is an estimate of the traffic data sent by the transmitter.
The coding and modulation performed by the transmitter have a large impact on the performance of the data transmission. There is therefore a need in the art for techniques to perform coding and modulation in a manner to achieve good performance.